Vehicles in recent years are equipped with an in-vehicle communication apparatus having a wireless communication function such as road-vehicle communication for performing wireless communication with roadside communication apparatuses installed on the road and vehicle-vehicle communication for performing wireless communication with other vehicles, enabling various types of information exchange to be performed with apparatuses external to the vehicle. A high level of security is desired in communication external to the vehicle that is performed by the in-vehicle communication apparatus, and communication technologies such as electronic signatures and encryption are generally used.
JP 2013-58140A, for example, proposes a communication apparatus that generates a vehicle ID from the vehicle number of its own vehicle and transmits the vehicle ID in addition to transmission data, and that also generates a vehicle ID after acquiring the vehicle number of another vehicle with which communication is to be performed and determines the validity of data received from the other vehicle through comparison with the vehicle ID attached to the received data.
In the case of performing communication that utilizes electronic signatures, encryption or the like, it is effective to utilize an issuing system for electronic certificate information that is configured by one root certificate authority and a plurality of sub-certificate authorities, for example. In this system, the root certificate authority issues the certificate information of the sub-certificate authorities and the sub-certificate authorities issue the certificate information of the in-vehicle communication apparatus. The certificate information that is issued by the sub-certificate authorities includes the certificate information of the sub-certificate authorities, in addition to information generated for the in-vehicle communication apparatus. The in-vehicle communication apparatus attaches an electronic signature including its own public key information and certificate information issued by the sub-certificate authorities to data to be transmitted by the in-vehicle communication apparatus. Another communication apparatus that receives this data is able to determine the validity of the received data, by determining the validity of the certificate information of the in-vehicle communication apparatus that transmitted the data, which is included in the electronic signature attached to the received data, and the validity of the certificate information of the sub-certificate authority that issued this certificate information.
It is not desirable from the point of view of security that one certificate information is used continuously over a long time period. As a result, certificate information often has a period of validity set therein and certificate information for which the period of validity has expired is often treated as invalid. The communication apparatus in this case requires that new certificate information is acquired when the period of validity of its own certificate information has expired or when the period of validity is about to expire. However, there is a problem that it is difficult for a conventional in-vehicle communication apparatus mounted in a vehicle to acquire new certificate information.
The present disclosure was made in view of these circumstances and an object thereof is to provide a communication system in which an in-vehicle communication apparatus mounted in a vehicle is capable of acquiring certificate information, and to provide an in-vehicle communication apparatus that is included in this communication system.